Dysrhythmias Flashcards
functions of cardiac cells
automaticity
excitability
conductivity
contractility
what is automaticity
ability to generate electrical impulse
what is excitability
ability of a cell to respond to an outside stimulus
- chemical, mechanical, electrical
what is conductivity
ability to receive an electrical impulse and conduct it
what is contractility
ability of the myocardial cells to shorten in response to an impulse
what is depolarization
when the muscles squeeze
- contractions in the atria and ventricles
- during systole
what is repolarization
when the heart is preparing to contract again
what is the p wave
the first little bump
- atria squeeze/depolarize
what is the QRS complex
the big jump
- ventricle squeezes/depolarize
- atria repolarize and get blocked by this
what is the t wave
the small bump after the QRS
- ventricles repolarize
what initiates the p wave
SA node
what initiates the QRS complex
AV node
how does the AV node know when to go
senses the depolarization of the atria
what are function of the bundle of HIS and purkinje fibers
responsible for telling ventricles to squeeze
normal electrical conductivity of the heart is called
sinus rhythm
what are the characteristics of sinus rhythm
60-100
regular
P waves are upright, rounds, before q QRS, regular
PR interval: 0.12-0.20 sec
QRS: less than 0.12 sec
what is the amount of time a little box represents on an EKG
0.04 secs
what is sinus arrhythmia
another normal commonly seen in young ppl
- degree of variability
- HR fluctuates with respiration or autonomic nervous system (longer p to p intervals)
- no changes of cardiac output
what is a dysrhythmia
abnormality of the cardiac rhythm
- problems w impulse generation or conduction
- significant bc it affects cardiac output
what are causes of dysrhythmias
inappropriate automaticity
triggered activity
re entry
what is inappropriate automaticity
a cell that initiates APs when its not suppose to
- can appear in the atria
- ex: myocardial ischemia, electrolyte imbalance
what is triggered activity
an extra impulse generate during just after repolarization
- ex: digoxin toxicity, SNS stimulation, genetics
what is re entry
cardiac impulse in one part of the heart continues to depolarize after the main impulse has finished
- myocardial ischemia, electrolyte imbalance